深藍光高解析度純相位矽基液晶空間光調制器於無光罩全像蝕刻之應用

Abstract

本實驗提出一簡單深藍光(405 nm)光路，離軸入射我們客製化的高解析度純相位矽基液晶空間光調制器，利用空間光調制器對雷射光束進行分光，並用其任意重構的特性，將任何欲蝕刻之圖案轉移到正型光阻(DFR110)上，最後顯影出目標圖形。 利用本實驗室之製程設備及製造技術，矽基液晶微型面板的均勻度誤差（標準差除以平均值）皆能小於1.5 %，本次設計之矽基液晶微型面板反應時間最快為2.83 ms。在面板量測上，藉由數位/類比驅動設定檔的程式碼編寫，匯入FPGA電路板，來進行液晶光電特性量測，而為了提高成像繞射效率並降低零階繞射效率，我們使用查找表look-up table (LUT)來進行驅動電壓對於相位調變的線性化。接著針對不同液晶及液晶盒厚度的面板，討論不同空間頻率光柵之繞射效率分析及空間形變對相位線性化的影響，希望往後透過驅動面板編碼進行損失相位的補償。線性校正完成的面板即可輸入用IFTA遞迴傅立葉演算法運算出之電腦全像片，以雷射光照射即可產生目標繞射圖案。在光阻蝕刻結果中，得到厚度約2 μm、線寬約35 μm的線條。

Arbitrary and reconfiguration pattern transfer photolithographic process using deep blue light source (405 nm) with off-axis phase-only beam shaping system is reported in this study. Three LCoS panel uniformity error are below 1.5 % with fast response time. Reconstructed diffraction images from CGH patterns were displayed on 8° off-axis screen/target plate. The linearly calibrated look-up table (LUT) showed better performance in suppressing the zero-order intensity. The phase modulation as a function of the spatial frequency was evaluated. The ghost image was solved as well. The diffractive images generated from linear LUT can be applied in the maskless lithographic pattern. The phase distribution displayed on the SLM are derived from the Gerchberg-Saxton (GS) iterative Fourier transform algorithm (IFTA) and generated desired light distributions by adjusting the phase of a uniform wavefront. A pattern consist of ~ 2 μm thickness and the period stripe pattern ~ 35 μm width was demonstrated with simplified optical system.